brake question

i have a question concerning a master cylinder. i purchased a pedal/power booster/m/c ***y from a vendor at the springfield nats to use on my 39 chevy. the question is, the master cylinder reservoir is divided into two chambers as all are except the older ones. both are the same size so which one would go to the front brakes and which to the rear? when i bench bled it fluid came from the rear port first and i ***ume that this should go to the rear brakes or should this be the fronts? everythings hooked up in this manner but im unable to get any pressure to build in the system. tried another m/c and checked the proportioning valve and it's clean not stuck still no luck. could this be from the lines reversed?thanks

 

A mushy pedal when you are trying to get them bled usually comes from one of three things.

1. Air in the lines
2. drum brakes out of adjustment by a bunch.
3. In some cases the lining on the shoes don't fit the drums well enough and the shoes flex a bit, The cure for that is arcing the shoes to match the drum.

My guess is that there is still air in the system somewhere.
Now I go back into my old autoshop teacher mode. Can you describe in detail exactly how you are bleeding the brakes?
The reason= I have seen more missinformaton on bleeding brakes on here and other forums in the past three or four years than I saw in the previous 45. I even had a guy here in my yard attempting to bleed a set of brakes and it was painfully obvious he didn't know what he was doing.

I'd suggest contacting the company that made the mastercylinder and booster or at least the company that puts their name on them to find out which end services which axle. Normally the front half serves the front axle.

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when both chambers are the same size it's usually for a drum brake system - bleed farthest away first ,
Also a different way to bench bleed is to plug the master at the ports -and use a 1" stroke - do not bottom it out -
also residual valves may have to be installed if not incorporated in the master - 2 lbs for disc - 10 lbs for drums , install downstream of proportioning valve

 

not a mushy pedal but no pedal at all even after several attempts to bleed out the system. when i put the system together i bled it out and could only get pressure to the front brakes and you could try the rears and no pressure at the bleeders, led me to think the p valve was stuck letting no fluid to the rear. new shoes and wheel cylinders. the last time i did this we power bled the system and this got front brakes but like i said no rear pressure had another new m/c at my disposal and cleaned the p-valve this is what i did today. i'm sure theres a little air in the system by just trying to do it manually but after the changes i cant get any pressure at the fronts which by the way are must II stock stuff. i'm going to try to force out the caliper pistons by air tomorrow as far as they will go without becomming dis***embled then fill the caliper to the top, shut the bleeder and then push the pistons back forceing the fluid back into the m/c. this alone should bleed out the fronts. but i was just unsure of line placement.

 

if the proportioning valve is OEM style -at the end under a rubber boot pull the pin about a 1/32" when bleeding

 

i had the same problem couldnt figure out why i had no pedal ...it was all air what i did was
jack it up all 4 corners wheels off crack all the bleeders and let it bleed it gravity bleed belive me it takes a couple hours but it works..but make shure your master dont run out of fluid or you will be doing this all over again .tighten up all the bleeders and than pump it up and begin bleeding from the furthest wheel should do it ..

 

Under floor systems will normally NOT gravity bleed. Be sure none of your lines are above the MC to form a air trap. With dual cylinders it works best to bleed the side closest to the booster/pedal no mater if it is front or rear. Make sure you have a residial check valve in the rear brake side.

 

Mr. 48chev can you tell us the proper procedure for bleeding a complete system? Or maybe post it as a tech article?

I just got my system hooked up today, gotta bleed it bleed it from the master on back so any help would be appreciated! Thanks